Create pull_request_template.md, update README, and auto-close PRs with message

.github/pull_request_template.md

@@ -0,0 +1,11 @@
+# Changes to This Repository Should Be Made in pecanproject/pecan
+
+Thank you for your interest in contributing to the PEcAn documentation!
+
+However, this repository is **automatically maintained** and synchronized from the `book_source/` directory of the [github.com/pecanproject/pecan](https://github.com/pecanproject/pecan) repository.
+
+HTML files in this repository are maintained as Markdown (MD) files in the source repository.
+
+If you have suggestions or improvements, please submit pull requests to the source repository instead.
+
+We appreciate your understanding and your effort to contribute!

.github/workflows/auto-close-pr.yml

@@ -0,0 +1,26 @@
+---
+name: Auto Close Pull Requests
+on:
+  pull_request:
+    types:
+      - opened
+permissions:
+  pull-requests: write
+jobs:
+  close-pr:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v3
+      - name: Install GitHub CLI
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y gh
+      - name: Authenticate with GH CLI
+        run: |
+          echo "${{ secrets.GITHUB_TOKEN }}" | gh auth login --with-token
+      - name: Close PR
+        run: >
+          gh pr close "${{ github.event.pull_request.number }}" \
+            --repo "${{ github.repository }}" \
+            --comment "Thank you for your interest in contributing to PEcAn documentation!\n\nThis repository is automatically maintained and synchronized from the book_source/ directory of the [pecanproject/pecan](https://github.com/pecanproject/pecan) repository.\n\nPlease submit your pull request there instead:\n[pecanproject/pecan](https://github.com/pecanproject/pecan)\n\nWe appreciate your effort and understanding!"

README.md

@@ -1,3 +1,13 @@
 # PEcAn Documentation Auto-build Repository
 
-Maintained by Robots: The materials here are compiled by Github Actions from source text in the main PEcAn repository (github.com/pecanproject/pecan). Please open issues and pull requests there.
+### :warning: This repository is **automatically maintained**. :warning:
+
+### **Pull requests** should be opened in the source repository.
+
+
+- Source text is maintained in the `book_source/` directory of the PEcAn repository ([pecanproject/pecan](https://github.com/pecanproject/pecan)).
+- The content here is compiled from the source repository via **GitHub Actions**.
+
+### Thank you for your interest in contributing to PEcAn
+
+And in particular, for helping improve our documentation!